NSF Funds Evolutionary Biomechanics Research

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Some species of mantis shrimp uses elastic energy to drive its hammer-like appendages at speeds greater than 60 mph to break open snail and crab shells. In order to better understand the physical principles of this capability, Harvey Mudd College physics professor Mark Ilton is studying the evolutionary biomechanics of extremely fast, small systems, a project recently funded by the National Science Foundation.

This research examines the causes, consequences and evolution of biomechanical variation in latch-mediated spring actuated (LaMSA) systems and the transitions between motor-driven and spring-driven movement within and across organisms.

During the next few years, research in Ilton’s Physics of Soft Matter Lab (PoSMLab) at Harvey Mudd will focus primarily on two guiding questions: What properties determine the maximum kinematic performance of elastic materials? And what principles govern the mechanics of biological LaMSA systems?

Ilton, who studies the dynamics of energy release in elastomers and impulsive biological systems, uses the example of an archer’s bow to describe LaMSA motion: “First a motor (the archer’s muscles) loads elastic energy into a spring-like element (the bow), which is held in place by a latch (the archer’s fingers). Upon releasing the latch, the stored elastic energy is rapidly converted into kinetic energy of motion. Some organisms have this combination of a loading motor, spring and latch built into their anatomy and can use it to perform ultra-fast movement.

“What’s perhaps even more impressive is that the performance of some of these biological LaMSA systems exceeds that of current engineering capabilities for repeatable kinematic performance at small sizes,” Ilton says. “By understanding the physical principles that govern these systems, our aim is to contribute to a better understanding of the evolutionary dynamics of these organisms and inform future engineering design.”

The $118,971 NSF grant provides support for two student researchers in the PoSMLab each summer for three years. “This summer, there were seven students working in PoSMLab on projects related to LaMSA systems, and we are submitting two manuscripts this fall based on that work,” Ilton says.

Students working on this project will help to further develop the model, write open-source software for the comparative biomechanics community and work with collaborators in biology (at Duke and the University of Hawaii, Manoa) and engineering (at University of Massachusetts, Amherst) to answer questions about mantis shrimp biomechanics.

“One of the most exciting parts about this work to me is that undergraduates at all levels can get involved,” Ilton says. “We have two senior physics majors doing their thesis work in PoSMLab this fall who are deeply exploring the materials physics of these systems. But we also have students who are new to research on the team. Students who have taken introductory mechanics and have some experience with programming can get involved and make an impact.”

Ilton joined Harvey Mudd’s Department of Physics in 2018 after working at the Conte Polymer Research Center at the University of Massachusetts, Amherst. He holds a PhD in physics from McMaster University.